How to restrict users from using Fiddle to submit multiple requests at the same time

For example, we have a sign-in request submitted by ajax. When the user submits the request, the php code roughly checks whether the user has signed in today. If the user does not sign in, sign in and increase the amount. However, some users can sign in multiple times through Fiddle. How can this problem be solved? I already... for example, we have a sign-in request submitted by ajax. When the user submits the request, the php code roughly checks whether the user has signed in today. If the user does not sign in, sign in and increase the amount.
However, some users can sign in multiple times through Fiddle. How can this problem be solved?

I have done token verification and limit_req_zone in nginx configuration, but it does not work.

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For example, we have a sign-in request submitted by ajax. When the user submits the request, the php code roughly checks whether the user has signed in today. If the user does not sign in, sign in and increase the amount.
However, some users can sign in multiple times through Fiddle. How can this problem be solved?

I have done token verification and limit_req_zone in nginx configuration, but it does not work.

Database transactions

Begin;
Sign-in Data Writing
Determine if (the database has written the incoming data) select id from table_name where*
Rollback
Else
Commit

Return sign-in successful